Hemp quality starts at the farm

Good agronomy is the starting point to ensure food-grade hemp

Hemp underseeded with hairy vetch.

Hemp processors are fixated on quality, and one of the most important links in that chain is at the farm level.

Jeff Kostiuk. photo: Hemp Genetics International

Jeff Kostiuk, Hemp Genetics International director of operations, Central Canada, U.S. & international, recently spoke to an audience at the Canadian Hemp Trade Association Conference about what practices growers should work towards when considering hemp.

Food-grade hemp crops are commonly tested three times. The raw farm sample is tested for microbes prior to processing. The product is cleaned then tested again. Then it’s processed and tested a final time. It is important to note that the nature of the processing means that it is unlikely things will change much through the process.

“There are kill steps, but there are not firm kill steps that will reduce or remove all of those microbes,” Kostiuk said. “So it’s extremely important that we start with a product we can work with and maintain that quality.”

Of course, that begins on the farm.

Although hemp has a reputation for being a tough crop, the young plant is quite fragile. As a result, seed placement, fertilizer placement and seedbed preparation is extremely important.

The ideal planting stand is in the 10- to 12-plant-per-square-foot planting range. If you go below that, while it might not affect yield, it’s almost certainly going to affect quality. If you go too wide with spacing, you’ll get a similar yield, but harvesting will be more expensive because the seeds can grow too close to the ground. You want to be able to harvest just the top third of the plant.

With 15-inch row spacing you get canopy closure within six to eight weeks and that’s when hemp starts to make that transition into a more durable plant. Once it starts to get its strong taproot established, it becomes more resistant to different issues.

The nutrient uptake on the total plant is 200 lbs. per acre of nitrogen.

“It’s a hungry plant,” notes Kostiuk.

Potassium is found mainly in the stalk. If you’re harvesting fibre that’s green, you’re removing the potassium, so keep an eye on those levels.

Hemp seed size varies substantially from between around 12 and 21 grams per 1,000 kernels. So, it’s vitally important to know the variety that you are seeding and you have to adjust for that seeding rate.

If you’re seeding in perfect conditions (for example, if you have a nice seedbed; your soil temperature is in the range of 10 to 20 C for a number of days; and you’ve got moisture at one-half an inch) your mortality level can probably fall below 20 per cent. But if you get a rain three days later and you have excess moisture, your mortality rate can rise to 70 per cent.

Seeding date trials were done in 2015 with five dates beginning in May and running to the first of July. The best results came from the third week in June. There was a significant drop-off for the July 1 results but that had more to do with poor weather conditions (there was basically no rain in July). However, there is definitely a trend that the earlier you seed the higher the mortality rate. So if you do need to seed earlier, you have to increase your seeding rate.

“To me the seeding date is what you feel in your heart and your gut. What the calendar says, what the forecaster says, put it all together and roll the dice,” Kostiuk said.

At harvest, the range of moisture is as low as nine per cent and as high as 18 or 20 per cent. But Kostiuk says if you can get it into that 12 to 13 per cent range, you’ll clean up your sample substantially and limit the amount of time you have to pay attention to the bin.

Hemp must be dried to below nine per cent moisture. Kostiuk recommends that you get your seed on aeration within four hours of harvest. That will slow down the microbial activity.

“A rule of thumb we use is for every horsepower of your aeration fan you want to put about 200 bushels of crop,” suggests Kostiuk. “If you’ve got some supplemental heat, you can maybe double that.”

He also noted that it is important to get a good volume of air and that 4,000-bushel bins shouldn’t be filled more than three-quarters full.

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